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In most animals, slow-wave sleep is characterized by high amplitude, low frequency EEG readings. This is also known as the desynchronized state of the brain, or deep sleep. In USWS, only one hemisphere exhibits the deep sleep EEG while the other hemisphere exhibits an EEG typical of wakefulness with a low amplitude and high frequency.
Sleep can follow a physiological or behavioral definition. In the physiological sense, sleep is a state characterized by reversible unconsciousness, special brainwave patterns, sporadic eye movement, loss of muscle tone (possibly with some exceptions; see below regarding the sleep of birds and of aquatic mammals), and a compensatory increase following deprivation of the state, this last known ...
Unlike most animals, whales are conscious breathers. All mammals sleep, but whales cannot afford to become unconscious for long because they may drown. They are believed to exhibit unihemispheric slow-wave sleep, in which they sleep with half of the brain while the other half remains active. This behaviour was only documented in toothed whales ...
While knowledge of sleep in wild cetaceans is limited, toothed cetaceans in captivity have been recorded to exhibit unihemispheric slow-wave sleep (USWS), which means they sleep with one side of their brain at a time, so that they may swim, breathe consciously and avoid both predators and social contact during their period of rest. [55]
Slow-wave sleep (SWS), often referred to as deep sleep, is the third stage of non-rapid eye movement sleep (NREM), where electroencephalography activity is characterised by slow delta waves. [ 2 ] Slow-wave sleep usually lasts between 70 and 90 minutes, taking place during the first hours of the night. [ 3 ]
Like other marine mammals, seals sleep in water with half of their brain awake so that they can detect and escape from predators, as well as surface for air without fully waking. When they are asleep on land, both sides of their brain go into sleep mode.
Before he ended his life, Ryan Larkin made his family promise to donate his brain to science. The 29-year-old Navy SEAL was convinced years of exposure to blasts had badly damaged his brain ...
The skull of the leopard seal. The leopard seal has a distinctively long and muscular body shape when compared to other seals. The overall length of adults is 2.4–3.5 m (7.9–11.5 ft) and their weight is in the range 200 to 600 kilograms (440 to 1,320 lb), making them the same length as the northern walrus but usually less than half the weight.